ATTENTION EVERYONE. After quite a bit of searching and not really realizing what I was doing, I was able to find the hardcoded resource path in the Paintstorm executable. As a result, I was able to hex edit the file and alter the path to be `/app/share/paintstorm`. Now, paintstorm works (kinda) in the flatpak sandbox. Some things are kinda wonky, but it shows up and painting works. I've put it in the gitlab repo https://gitlab.com/Miridyan/paintstorm-flatpak. Please feel free to play around with it! I'm super happy I was able to get this working. Please submit any and all issues you find to the issues section on my repo. Thanks guys!

Thanks, allthecoffee. I'm just not able to get away with the flatpak/git stuff. Such a newb with Linux, but thankfully very happy with Krita now. if the libinput issue is fixed, I'll look at PSS again. Much appreciate your great work on this. Very good of you.

Flatpak doesn't work well with LM (deb/appimage/.sh work directly, if that's helpful), but a very big thank you indeed to you, and Cestarian, for all the exemplary work done to attempt to get PSS to work fully on Linux.